US2725438A - Alternating current switch mechanism - Google Patents

Description

5 Sheets-Sheet l Nov. 29, 1955 R. H. BENTLEY ALTERNATING CURRENT SWITCH MECHANISM Filed Sept. 15, 1952 Nov. 29, 1955 R H, BENTLEY 2,725,438

ALTERNATING CURRENT SWITCH MECHANISM Filed Sept. l5, 1952 5 Sheets-Sheet 2 Irvs/e., 1:- Roberfflewioy/ 7l/fris Hamm-,QQ

MQW/Mw- Nov. 29, 1955 R. H. BENTLEY ALTERNATING CURRENT SWITCH MECHANISM 5 Sheets-Sheet 3 Filed Sept. l5, 1952 I enfor- RO erB eJr,

Nov. 29, 1955 R. H. BENTLEY ALTERNATING CURRENT SWITCH MECHANISM 5 Sheets-Sheet 4 Filed Sept. 15, 1952 HMM NOV. 29, 1955 R. H. BENTLEY ALTERNATING CURRENT SWITCH MECHANISM 5 Sheets-Sheet 5 Filed Sept.. 15, 1952 United States Parce@ 2,725,438 ALTERNATING CURRENT SWITCH MECHANISM Application September 15, 1952, Serial No. 309,689 23 Claims. (Cl. 200-67) This invention relates to electric switches for use in alternating current circuits` More particularly itrelates to a mechanism which will quietly open and close the switch contacts especially of the butt type. Additionally, it relates to such a mechanism which separates the contacts slowly for a short distance in initial stages ofV switch operation.

With the growth of the electrical industry there have been less and less uses of direct current for domestic purposes such as for house wiring. Likewise, the use of direct current in cities has almost disappeared. Hence the original need for switches which open the contacts and close them with a snap action has now largely disappeared. It has long been known that for ordinary house wiring voltage and current requirements, slowopening contacts were satisfactory and that expensive, complicated and noisy snapswitch mechanisms were not essential to satisfactory circuit-breaking action. Also, butt type contacts were satisfactory and often preferable in alternating current work.

The vogue for housing wiring switches of the type which are mounted in the Wall to be operated when a person comes into or leaves a room and for other related uses has long been for the lever-type; and there has been a demand for such switches which would operate quietly. The snap switch mechanism commonly used heretofore in lever-operated switches caused considerable noise when the switch lever reached the end of its travel. Efforts to overcome this objectionable click or snap have resulted in conventional snap mechanisms provided with rubber bumpers and in devices embodying mercury contact arrangements. Generally speaking, they have not been satisfactory or, in the case of mercury switches, the use of fragile and expensive glass elements has increased greatly the cost of the switch and liimted its field of use.

Therefore, it is an object of my invention to provide a novel lever-operated electric switch mechanism which may be economically manufactured and will be reliable and quiet in operation. t f -f Another object of the invention is to provide a quietlyacting switch of the above mentioned type wherein the lever will positively move from one position to the other when released by the hand of the operator thus to give to the operator the .feeling of satisfaction .and confidence that the switch has operated properly.

Another object of my invention is to provide a butttype lever operated switch for alternating current house wiring and related uses which will at the same time satisfy the aforesaid objectives.

Another object is to provide a quietly-acting butt-type switch achieving the above objectives which will also pass ythe underwriters tests and be acceptable for general usage in houses and elsewhere.

Another object .is to provide a butt contact type .of switch possessing one or more, or all, of the foregoing features and also ha-ving superior arc-interrupting capacities. Arelated object is to provide `for slow initial separation of the contacts to a predetermined distance .for

; 14s which It has a flat body portion 14 extending 2 optimum arc-extinguishing characteristics followed by a further separation for adequate final separation. Another related. object is to provide in such a switch for slow ini'- tial opening of the switch contacts followed by rapid final switch opening movement. .A

Another object is to provide a double-throw switch having one or more of the foregoing features which will opcraie with equal arc-quenching effect and/or silently in both directions. j

Other objects and advantages of the invention will become apparent as it is described in connection with the accompanying drawings.

t This application is a continuationein-part of my copending application Ser. No` 267,052, tiled January 18,

1952, entitled AlternatingCurrent Switch Mechanism, abandoned October 17, 1952.

in the drawings:

Figs. l and 2 are longitudinal section views of the switch embodying the invention, in two diderent positions of the mechanism,

Figs. 3 and 4 are detail perspective views of the wire terminals with movable and xed contacts attached respectively,

Fig. 5 is a plan view of the interior of the switch base with the contacts and terminal members in place,

Fig. 6 is a'detail perspective view of the overcenter spring support shown in Figs. l and 2,

Fig. 7 is a diagrammatic, view showing the force actions in various switch positions,

Fig. Sis a perspective view of the operating lever,

Figs. 9, l0 and ll kare diagrammatic views of three other different forms of theinvention.

' Referring to the drawings, the parts are mounted upon a base 10 made from any suitable insulating material, which is hollowed out for the reception of the fixed and movable switch parts. At one end of the base is mounted a combined wire terminal and contact member which may be stampedV conveniently from `sheet metal into the form illustrated in Fig. 4. A flat body portion 12b extends fromfront to back into the base il) at .one end and has a terminal plate 121 bent laterally therefrom to be along side the interior wall lengthwise of the base near one end, The base is cut away' adjacent a portion of the terminal plate to accommodate a terminal screw 13 and for aix ing wires when desired. A supporting finger 12a is bent at right angles to the body portion 12b and a contact button 12c of silver is mounted on the underside of the finger 12a. A

Adapted to engage and disengage the fixed contactbntton 12a` is a movable contact .button 14e` mounted upon the end of a movable contact supporting `member may' be conveniently formed from a strip of resilient thin sheet metal. This movable contact supporting member is mounted at its .opposite end upon a wire terminal and supporting member which may also be stamped from sheet metal as illustrated in Fig. 3. from :front .to rear of the base at the end opposite terminal 12. A terminal plate 142 bent at right angles to the .body por-v tion 14 lies alongside of the .inner wall of ,thebase which is` recessed adjacent the plate for a terminal screw 15.

' The movable contact'member .thus extends from one end side wallsof :the switch base.

of the switch base to the other. Above it and pi-.votally mounted :on thevbase is Yalcontact operating `lever 20 which is preferably molded from insulating material `into described.

The contact operating lever may have an .extending handle' `portion 21 of conventional shape adapted to lit Wit-hin the usual vrectangular .aperture of the conventional switch -or wall plate. Trunnions 22 extend laterally from the Ilever and are seated in bearing recesses v24 in the 'Extending linto the base 2,725,4ss i from the lever preferably at one side of the center plane thereof is a cam member of V-shape with its end rounded and adapted toengage the movable contact and supporting member 14s to operate it. This operating cam has its center line located in a plane perpendicular to the base of the switch (and to the wall plate which is usually used over the base) when the cam is in position to cause separation of the contacts 12e, and14c, as may be seen in Fig. l. In this position, the handle 21 will be at an angle approximately to the right of the center line or center plane. When the handle is moved to the opposite position or in other words, to a position about 30 on the left side of said center line, the operating cam 25 moves counterclockwise and disengages the movable contact supporting member. The resilience of the movable contact supporting member then causes that member to move into position wherein its button 14e engages the button 12e of the tixed contact.

In order to positively move the lever member 20 and to hold it in its two opposite positions, I provide an overcenter spring device comprising a coiled compression spring 30 having circular, cup-shaped, bearing caps 31 and 33 on its upper and lower ends. The bearing cap 31 on the upper or outer end of this spring engages with an operating finger 34 extending inwardly from the operating lever along the center line thereof and tapering towards its end to a rounded point for engagement with said bearing cap 31. The inner or lower end of the spring has its bearing cap 33 resting upon a fulcrum or pivot point 41 formed upon a U-shaped fulcrum member 49 which conveniently may be stamped from sheet metal into the form illustrated in Fig. 6. The location of this point is of importance and as will be explained, the point is oiset from the transverse median plane through the pivotal axis of the switch operating lever 20, differing from prior practice when overcenter springs were used. The parallel side arms of the fulcrum member may conveniently be slid in opposite parallel grooves 43 formed in the side walls of a well 44 in the center of the base 10 wherein the spring pivots to and fro.

To halt the movement of the operating lever quietly at the proper positions and also to deaden the sound of the movement of the operating lever moving into one or the other of its positions, bumpers 46 made of rectangular blocks of sponge rubber or other soft resilient material are provided at either end of the well 44. The ends of the operating lever are attened to abut the iiat top surface of the bumpers in the two positions of the lever; and any overtravel of the spring in the position of Fig. 2 will be taken up by abutting against the opposing faces of the bumpers until the several forces of theY moving parts are in equilibrium. The mechanism is designed and proportioned, however, to avoid abutment of the spring with the rubber bumpers. Since the operating lever comes to rest against and is stopped by the top of the rubber bumpers, it limits the movement of the spring so that the spring need not abut the bumper; but if the spring should overtravel, its motion has been so retarded, at that time and position, that no considerable click can result from that cause. The only moving part other than the contacts, which is designed to have its motion stopped by engagement with a stationary part is the operating lever 20; and since it engages quietly with the-bumpers 4 6, the switch operates silently.

When it is desired to provide contact arrangements for a three-way or double-throw switch, a contact and terminal member may be provided comprising asheet metal stamping having a flat body portion Slat the nal plate to accommodate a terminal screw. YFrom the top edge of the body 51, a flat extension 53 is bent at right angles toward the middle of the base from the end of which an arm 54 extends laterally and downwardly toward the opposite side of the base to a point beneath the end of the movable contact carrier 14s. On the bottom side of the end of the carrier 14s is a contact button 14k which is adapted to engage a similar fixed contact button 55 on the top side of the end of the arm 54 when the switch handle 21 is in the right hand position. The

pressure of the cam 25 on the resilient contact carrier 14s will provide the necessary pressure to hold contacts 14k and 55 rmly engaged. After movement of the handle 21 through a small angle from right to left, contact carrier 14s will graduallybe released and its resilience will cause disengagement of contacts 14k from fixed contact 55.

In prior switches employing an over-center spring which acted to cause the movable contact to operate with a snap motion and which also acted upon the handle, the forces Whichacted upon the handle were equal in each direction of travel. Users have become accustomed over the years to expect` such a feel Aof the handle as indicative of normal and proper switch functioning.

According to my invention, the parts are arranged and the forces are designed to interact so as to develop substantially equal forces on the vhandle in each direction of its travel, despite the disrupting eifect introduced by the spring force of the contact supporting member k14.

For better understanding of the novel interaction of forces as employed in this invention, reference is made now to Fig. 7. As the handle moves from the right to the left position, its center line moves from the line b-b to the line a-a. In so doing, it moves through the line c--c wherein the handle is perpendicular to the switch base. In prior switches (but not in this switch) this was commonly the overcenter point or dead center position.

As the handle moves from right to left, the overcenter spring has its line of action moved from the line x-x to the line y-y. In so doing, it passes through the pivotal axis of the handle at the line z-z which is angularly spaced from the perpendicular, c-c.

When the handle is at the right, the movable contact operating cam 25 acts in a plane perpendicular to the movable contact carrier 14s. This is the plane of line c-c as shown in Fig. 7.

In the left position the contactoperating cam 25 has moved to the line p--p where it exerts no force and is disengaged from the movable-contact carrier 14s. disengagement is designed to take place (on moving the handle from right to left) before the overcenter spring reaches the dead center position. This disengagement eliminates the spring force of the contact carrier from g action on the cam 25 and operating member 20. Since the -spring force of the movable contact carrier 14s at all other times acts on the cam 25, its inherent spring force aids the handle movement to the left initially but opposes its movement to the right as soon as the cam 2S engages the spring carrier 14s and starts to separate the` contacts 12e and 14e.

` In order to substantially equalize the pressure or force needed to move the handle in each direction for operating the switch and also to equalize the pressure exerted by the mechanism on the handle at the end of its travel same end of the switch base 10 as the member 12b but at the other side of the base. The body 51 extends from front to rear of the base in slots as do the body portions of the other terminal and contact members. From the outside edge of the body a dat terminal plate 52 is bent at right angles to lie along the inside Wall of the base;

andthe side wall of the base is open alongside the termiin each direction, it is necessary to balance the com? bined effects of the spring forces of the contact carrier 14s and of the overcenter spring 30. It is for that reason that the mounting of the lower or inner end of the overcenter spring is offset from the centerline c-c. By that offsetting, the component F of force of the overcenter spring acting tangentially to the radius of the spring operating nger 34 at the point of application of the spring force in the right position of the handle is greater than the corresponding component (not illustrated) in the left position. But in moving the handle from right to left position such greater component of This K grasses 5 .force opposing such opera-tten is in partv neutralized by the aid that the force of Ythe contact-'carrying spring starts to exert as soon as the move-ment of the handle toward the left starts.

Such aid however ceases as or before' the overcenter spring reaches the dead-center or z-z position (because the cam 2S disengages the contact spring 14s before that event) so that thereafter only the overcenter spring 4force acts to complete the movement vof the handle to the left.

As stated, 'on movement of the handie from left to right position, 'a lesser component of the overcenter spring force has to Vbe overcome than the component which acted when the switch handle was being moved the other way. This lesser component is approximately equal to the greater component minus the force of the carrier spring 14s which is encountered .in moving in the other direction. The Iovercoming vof this lesser component continues until the dead-'center or z-z position cf the spring is reached. Thereafter the component of the overcenter spring 'and the handle carrying 'them on past dead-center builds up in Yopposition to 'the counter-force of the movable-contact-carrying spring 14s until the parts come to rest with the handle in the right hand position.

Comparing the composite of forces acting on the operating lever 20 as the handle moves past dead-center position (z-z), it will be .noted that in movement after dead-center from left to right yby the handle, the overcenter spring is opposed by the `contact carrier 14s. The resultant is substantially equivalent to the lesser force component of the overcenter 'spring which alone 'acts after dead-center in movement of the handle from right to left.

From the foregoing, it will be observed 'that have provided an arrangement of 'switch contacts and operat ing mechanisms in which the forces acting `upon the switch handle in both open and closed positions are equal in a butt contact type of switch wherein the contacts are normally biased into `one position and wherein the switch opera-tes quietly. Moreover, the equalization of forces as above described `'avoids the excessive force in one direct-ion vor 'another as would result fif the pressure of the contact-carrying v'spring were 'merely aggregated to the handle biasing spring.

-It is now well known that if contacts are separated slowly in alternating current circuits, preferably to an optimum distance, 'the current has an opportunity to pass through zero while the contacts are separating. .Hence the tendency of the arc to draw Vout and prolong -is retarded and counteracted. After the contacts have sepaL rated slowly, a small distance, so .as to give fthe arc suppressing tendency an opportunity to function, it Ais desirable to move the contacts apart, further and 'more rapidly, to a predetermined .and desired distance.

To provide for the slow initial separation 'and more v rapid -tinal movement, the structure illustrated in Figs. Sand l0 may be incorporated in the invention previously described- In Fig. 9 the operating member 120 is mounted on trunnions 122 and has a handle 121. 114 carries a flexible contact supporting member 114s and is operated by a cam member 125 on the operating member 12). The contact button 114e on the end of the contact support 114s iis adapted to lengage 'and disengage the'xed contact button 11,21;` on wire terminal 112.

However, to cause rapid opening after initial separa tion, a concave V-shaped deformation 114v is formed `in the portion of the contact support 114s which is 'engaged by the cam 125. This V-porticn `is so formed that as the c'am 125 engages and moves down one side of the ccncavity, the contact support will be caused to move slightly and will separate the contact button 114C from button 112e, slowly, a predetermined distance as yshown in dotted lines Fig. 9.

lWhen the cani has moved from line d-d through angle A Ywire terminal .l

4ment of the contacts apart.

e to line mm, the advancing icam face will abut the 'ascending opposite face ofthe V-shaped concavity. From that position onward as the rotation of the camV and operating member is continued, the camming action is effective at a steeper angle thus causing a greater movement of the Contact supporting strip 114s and more rapid movement from the contact 112C. Thus, more rapid movement continues while the operating member and cam move through 'the nal angle h to the dot-dash line position o-o, at which position the full degree of contact separation is achieved.

Although for clarity the spring 30 and associated parts are not shown in Fig. 9 or in Fig. 10 about to vbe described, it will be understood that they are or may be employed for the same reasons and .functions as have already been described.

in Fig. 10 is illustrated another form similar in function to Fig. 9, but dilfering in details of construction. In this form the operating member 220 has a handle 221' and is pivotally supported by trunnionsV 2722. The terminai 214 has flexible contact supporting strip 214s mounted at one end thereon. vMovable contact button' 214:.` on the other end of the strip lengages and disengages fixed contact button 212C on terminal 212.

The cam 225, in this instance, is adapted to engage a ila-t portion of the contact support 214s. The cam has a flat portion '5225a spaced from the at portion of the con-tact supporting strip 214s. The dat portion 225a merges into anarcuate portion 22511 concentric with trunnions 222 and joining a round hump or high 'point 225C.

As the handle 221 is moved clockwise from the posi- -tion of Fig. 10, cam 225 rotates. During the rst small angle of rotation, i. e. until the beginning of surface '2255 comes into engagement with the at portion, the contact supporting strip, there is no motion of the contacts. Thereafter, the surface 225k exerts a camming action on the `strip, slowly separating contact button 214e from `button 2.12ct. This slow separation continues until the cam hump 225C reaches the dotted line position nn of Fig. l10. Thereafter, the increased camming angle and action of surface 225C will cause more rapid `contact Aseparation -a's the contacts continue -to move apart until they reach the position shown in dot-dash lines o o in Fig. 10. IAt that position the contacts have reached their maximum separation.

From the foregoing it will be understood that both 'the forms, Fig. 9 and Fig. r10 provide slow limited initial `contact separation followed Aby more rapid final move- Actual tests 'show these functions added by the novel structure of Figsf9 `and 10 to give superior operation and to possess arc suppressing characteristics of .high order.

In Fig. 1.1 Vis shown another form generally similar to Figs. 9 and l0 but wherein a dwell or hesitation `is provided in the movement of the contacts between the original separation and the llinal position.

The operating handle '321 pivotally mounted on 'trunnions 322 has its cam engaging the flexible contactsupporting strip 314s mounted lon the terminal 314 at one end and carrying the moving Contact 'button '314C on top of the other end. This button engages and di'sengage's fixed button 312e on terminal 312. On the other (or bottom) surface of 1the strip opposite the top button 314e` may be a bottom button 314k for engagement with 'a lower 'stationary contact rbutton 35S on a 'different 'terminal 356, in case a double throw or three-way 'switch is desired.

In Fig. y11 the contact strip has a half-round lcylint'l-ric'al or arcuate portion I31451 in its mid-'portion for -engagement with'the cam sur-faces lon the operating lever. These cam Asurfaces are 'most conveniently flat in 'lateral extent but Vmerge one into the other peripherally. From about the level or a diameter equal to that of 'the trunnons 322, cam surface 325g curves convex'ly upward merging into yanother arcuate cam surface 32611 which is concentric with the axis of trunnions. Surface 32i6b continuing for a short distance of say 15 more or less depending on the conditions of use and requirements of design, merges into another convex arcuate cam surface which rises sharply. The curvatures of cam surfaces 325:1 and 325e determine the speed of movement of the contact during engagement and disengagement; and the amount of their rises to and above the surface 325b respectively determines the degree of initial and final separation of contact button 314C from 312C. The reverse applies as to contact button .3l-tk and iixed contact button 355 since in the fully open position of contacts 312C and 314e the contact 314 is engaged with contact 355.

As the operating lever is moved clockwise from the full line position (position P) of Fig. 1l, cam 325e moves into engagement (position f) with the half-round Sida on the movable contact supporting strip causing that strip to move away from iixed contact 312 into the dotted line position as the cam 325a rides over the half round 314m As surface 325b rides over the half-round 314g during continuance of the movement of the operating lever, the contacts remain substantially stationary.

When iinally during the end of the movement of the operating lever the surface 325C engages (position r) and rides over the half-round 314s the contact 314e is forced further from the lixed contact 312C. Simultaneously contact 314k is pressed into engagement with contact 355.

Thus the contacts 312C, 314e will separate initially with' a slow motion to a predetermined distance which will be the optimum distance for arc suppression and extinguishment and thereafter will hesitate or halt and then continue on its path to fully separated position.

The reverse will occur on reverse movement of the l2- operating lever.

Besides the added functions of arc suppression on reverse operation in double-throw switches the form of Fig. l1 has manufacturing advantages due to the form of the movable contact supports.

Many other modiiications embodying the principles of the invention will occur to those skilled in the art. Therefore, 1 do not limit it to the precise forms illustrated and described.

What I claim is:

1. An'electric switch comprising a housing a manualiy operable lever movable about a pivotal axis between two at-rest positions, an actuating member movable with said lever member, xed and movable contacts, a movable contact carrier biased toward said actuating member, said actuating member engaging said contact carrier to operate the movable contact from one position to another against said bias, over-center spring means engaging a portion of said lever member and biasing said lever member into one or the other of its two positions, said spring means being supported at one end by said lever member, and means supporting said spring means at its other end from said housing, the position of said spring in said two positions of said lever member causing its bias of said lever into said two positions to be different in amount and opposite in direction to compensate for the biasing action exerted by the contact carrier on said lever member.

2. An electric switch comprising a housing a manually operable lever member movable about a pivotal axis between two at-rest positions, an actuating member movable `with said lever member, iixed and movable contacts, a movable contact carrier biased toward said actuating member, said actuating member engaging said con- Atact carrier to operate the movable contact from one position to another against said bias, said carrier exerting a force on said lever member as it moves into and from one position, spring means biasing said lever member into one or the other of its two positions, said spring means being supported at one end by said lever member,

and means supporting said spring means at its other end from said housing, the position of said spring Yin said two positions of said lever member causing its bias of said lever into said two positions to be dierent in amount and opposite in direction to compensate for the biasing action exerted by the contact carrier on said lever member.

3. An electric switch comprising a housing a manually operable lever member movable about a pivotal axis between two at-rest positions, an actuating member movable with said lever member, xed and movable contacts, a movable contact carrier biased toward said actuating member, said actuating member engaging said contact carrier to operate the movable contact from one position to another against said bias, said carrier exerting a force tending to-move said lever member in the direction of its motion when it is moving toward one position and exerting a force opposing movement of said lever when it is moving in the other direction, spring means biasing said lever member into one or the other of its two positions, said spring means being supported at one end by said lever member, and means supporting .said spring means at its other end from said housing, the position of said spring in said two positions of said lever member causing its bias of said lever into said two positions to be ditferent in amount and opposite in direction to compensate for the biasing action exerted by the contact carrier on said lever member.

4. An electric switch comprising a housing a manually operable lever member movable about a pivotal axis between two at-rest positions, an actuating member movable with said lever member, iixed and movable contacts, a movable contact carrier biased toward said actuating member, said actuating member engaging said contact carrier to operate the movable'contact from one position to another against said bias, said carrier exerting a force tending to move said lever member in the direction of its motion during the iirst part of its travel when itis moving toward one position and exerting a force opposing movement of said lever when it is moving in the other direction, spring means biasing said lever member into one or the other of its two positions, said spring means being supported at one end by said lever member, and means supporting said spring means at its other end from said housing, the position of said spring in said two positions of said lever member causing its bias of said lever into said two positions to be different in amount and opposite in direction to compensate for the biasing ction exerted by the contact carrier on said lever mem- 5. An electric switch comprising a housing a manually operable lever member movable about a pivotal axis between two at-rest positions, an actuating member movable with said lever member, fixed and movablecontacts, a movable contact carrier biased toward said actuating member, said actuating member engaging said contact carrier to operate the movable contact from one position to another against said bias, said carrier exerting a force tending to move said lever member in the direction of its motion during the first part of its travel when it is moving toward one position, and exerting a force opposing movement of said lever during the last part of its travel when it is moving in the other direction, spring means biasing said lever member into one or the other of its two positions, said spring means being supported at one end by said lever member, and means supporting said spring means at its other end from said housing, the position of said spring in said two positions of said lever member causing its bias of said lever into said two positions to be different in amount and opposite in direction to compensate for the biasing action exerted by the contact carrier on said lever member.

6. An electric switch comprising a housing a manually operable lever member movable about a pivotal axis between two at-rest positions, an actuating member movable with` said lever member, xedand movable contacts, a movable contact carrier biased toward saidactuating member, said actuating member engaging saidy contact carrier to operate' the movable contact from one position to another against said bias, said carrier exerting a force tending to move said lever member in the direction of itsmotion when it is moving toward one position and exerting a force opposing movement of said lever during the last part of its travel when it is moving, in the` other direction,I spring means biasingl saidlever member into one or' the other of its two positions, said spring means being', supportedy at one end by said lever member, and means supporting said spring means atits other end from said housing,- the position of said s'pringrin said two posi-` tions of said: lever member causing its bias' of said lever into saidt-wo positions to be different in amount and opposite in direction to` compensate for the biasing action exerted by the contact carrier on said lever member.

7. Anv electric-switch comprising a housing a manually operable-lever member movable' about a pivotal axis between two at-'rest positions, an actuating member movablel with said lever member, fixed andl movable contacts, a. movable contact carrier biased toward said actuating member, said actuating member engaging said Contact carrier to operate the movable contact from one position to another against said bias, spring means biasing said lever member into one or the other of its two positions, said spring means being supported at one end by sai'dl lever member, and means supporting said`v spring means at itsl other' e`r'id from said housing, the position of said spring in said two` positions of said lever member causing its bias of said lever into said'. two positions to be dierent irl amount and opposite in direction to compensate for the biasing action exerted by the cont-act carrier on` said iev'e'r member, said carrier exerting a force on said lever membe'rwhen said lever member and spring means are on one side but not whenthey are on the other side of mid-point of their combined actions.

8.-V Arr electric switch comprising a housing a? manually operable lever member movable about a pivotal axis between two at-rest positions, an actuating member movable with said lever member, fixed and movable contacts, a movable contact carrier biased toward said actuating member, said actuating member engaging said contact carrier to operate the movable contact from one position to another against said bias, spring means biasing said lever member into one or the other of its two positions, said spring means being supported at one end by said lever member, and means supporting said spring means spring in said two positions of said lever member causat its other end from said housing, the position of said ing its bias of said lever into said two positions to be different in amount and opposite in direction to compensate for the biasing action exerted by the contact carrier on said lever member, said movable contact engaging said xed contact before said spring means exerts its biasing action toward switch-closed position and thus eliminating the action of the carrier on the lever member during further movement in switch-closing direction.

9. An electric switch comprising a housing a manually operable lever member movable about a pivotal axis between two at-rest positions, an actuating member movable with said lever member, fixed and movable contacts, a movable contact carn'er biased toward said actuating member, said actuating member engaging said contact carrier to operate the movable contact from one position to another against said bias, spring means biasing said lever member into one or the other of its two positions, and said spring means being supported at one end by said lever member, and means supporting said spring means at its other end from said housing, the position of said spring in said two positions of said lever member causing its bias of said lever into said two positions to be different in amount and opposite in direction to compensate for the biasing action exerted by the contact car- 10 rier oni said levermemben, said movable contact` remain:- ing engaged until said spring means starts to exert its biasing action ini switch-opening.. direction.

10: A switch as claimed in vclaim 2 havingy resilient noise absorbent` means engageable by said? lever member quietly to limit the movement of said lever mem:- ber.

1f l. An electric switch comprising' a housing, -a manually operabler lever member movable about apivotal axisv between twol po'sitions, an actu-ating member movable with said lever member, fixed and movable contacts,vv a movable contactcarrier biased toward said actuating member, said actuating.` member engagingA said contact carrier to operate the movable contact from` one position tof another against said' bias, over-center springf means en-` gaging a portionv ofsaid4 lever member an'd biasing said lever memberv into one'orl the'other" of. its two positions,- saidspring meansy bei-ng supported at oneA end* by said lever member, and means supporting said spring means at its other end fromsaid housing, theA position of said spring in said two posit-ions of said. lever memberv caus-` ing the bias of said lever into said two positions tol be differentr in' amount and: opposite in direction4 to compensate for the biasingy action exerted by the contact car'- rieroni said: lever member', and' means associated with said actuating member` and contact carrier to cause separation of said contacts slowly and after predetermined separation toy continue separating movement more rapid- 1r- 112. Aswitchf as-clamed infclaim 1l whereinI the meansassociated with. the actuating member and contact cari rier comprise mutually cooperating cam surfaces ot dif'- ferent extent' andi inclination, i

13. An' electric switch comprising ahousing, a manually operable lever member' movable about a pivotal axis between-'two positions,v an actuating member movable with=y said lever mem-ber', 'xed' andE movable contacts, a movable` contact carrien biased' t'ov'vard said? actuating member, said'- actuating member engaging'- said contact carrier to operate the movable contact from one position to another against said bias, over-center spring means engaging a portion of said lever member and biasing said lever member into one or the other of its two positions, said spring means being supported at one end by said lever member, and means supporting said spring means at its other end from said housing, the position of said spring in said two positions of said lever member causing the bias of said lever into said two positions to be different in amount and opposite in direction to compensate for the biasing action exerted by the contact carrier on said lever member, and interengaging cam surfaces on said actuating member and contact carrier, the relative inclination of certain portions of the surfaces causing slow initial contact separation, the relative inclination of other adjacent surfaces causing more rapid continued contact separating movement as said actuating member is moved further without substantial variation. in rate.

14. An electric switch comprising an insulating casing, a fixed contact mounted therein, a movable contact engaging and disengaging said xed contact, a molded insulation operating handle having molded trunnions seated in bearings in the wall of said casing, a cover for said casing engaging said trunnions and holding them in their bearings, a flexible contact carrier biased toward said handle, an operating cam molded integrally with said handle and engaging said carrier to operate said movable Contact, a finger on said handle, over-center spring means engaging said finger, a seat for said spring means located in the bottom of said casing, said seat being offset to provide a larger component of force in one at-rest position of said switch than in the other, said larger component compensating for the force exerted by the bias or said carrier on said handle in said other position.

15. A switch as claimed in claim 14 wherein the spring 11 seat in the casing bottom comprises. a U-shaped metal member. f

16. A switch as claimed-in claim 14 wherein the spring seat in the casing bottom comprises a U-shaped metal member, and slots in the casing into which the arms of said U-member fit to enable the stamping to be dropped into place in the casing. v

l7. A switch as claimedin claim 14 wherein the spring seat in the casing bottom comprisesv a U-shapedmetal member, and slots in the casing intor which the arms of said U-member fit to enable the stamping to be dropped into place in the casing, the transverse portion of the U-member being offset from the plane of said arms.

1S. A switch as claimed in claim 14 wherein the spring seat in the casing bottom comprises a U-shaped metal member, said U-member having parallel arms and a transverse portion offset from the plane of said arms.

19. An electric switch as claimed in claim 2 having oppositely facing -contacts on said contact carrier, two fixed contacts alternately engageable by the contacts of said Contact carrier when said switch is alternately in its two positions. Y

20. Anelectric switch as claimed in claim 1 having oppositely facing contacts on said contact carrier, two fixed contacts alternately engageable by the contacts of said contact carrier when said switch is alternately in its two positions. v

21.,An electric switch as claimed in claim 5 having oppositely facing contacts on said contact carrier, two

fixed contacts alternately engageable by the contacts of said contact carrier when said switchis alternately in its two positions.

22. in an electric switch, amanually operable lever movable about a pivotal axis between two at-rest positions, an actuating member movable with said lever mem- V ber, two iixed contacts, a movable contact carrier, movable contacts on said carrier alternately engageable by said movable contacts when the switch is alternately in its two positions, and interengaging cam surfaces on said actuating member and contact carrier, the relative inclina- Y tion of certain portions of the surfaces causing slow initial contact separation, the relative inclination of other adjacent surfaces causing more rapid continued contact separating movement as said actuating member is moved further without substantial variation in rate and regardless which of said fixed contacts is being disengaged.

23. An electric switch comprising a manually operable lever movable about a pivotal axis between two at rest positions, an actuating member movable with said lever member, fixed contacts, a Contact carrier movable between said iixed contacts, movable contacts on said-car rier alternately engageable with saidvxed contacts when the switch is alternately in its two positions, and interengaging cam surfaces on said actuating member and contact carrier, the relative inclination of certain portions of the surfaces causing slow initial contact separa? tion, the relative inclination of other adjacent surfaces causing more rapid continued contact separating movementas said actuating member is moved further without substantial variation in rate, said cam surfaces being operable in both directions of movement of said actuating member and regardless engaged.

References Cited in the le of this patent UNITED STATES PATENTS which fixed contact is being disf

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